A method for measuring substrate noise in the UWB frequency band on lightly doped substrates

A measurement method for characterizing the substrate noise over the ultra-wideband (UWB) frequency band in UWB systems implemented using lightly doped CMOS processes is presented. The measurement structure in this method is based on modified ground-signal-ground (GSG) pads. In addition, the effects of the distance-based substrate resistance and the capacitive coupling between the substrate and the ground of the measurement setup are evaluated by on-wafer measurement of a test chip fabricated in a 0.18 μm lightly doped CMOS process. An equivalent circuit model of the presented measurement structure is given and shows accurate fit. From the measurement results the presented method is shown to provide a measurement band from 3 GHz to 10 GHz. To further validate the usability of the method a practical class-E PA is used.